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Philosophy Notes Metaphysics Notes

Dualism Notes

Updated Dualism Notes

Metaphysics Notes

Metaphysics

Approximately 46 pages

6 undergraduate essays and one essay plan in the Metaphysics module of Part 1A of the Philosophy Tripos at Cambridge. Topics are:
Induction
Personal Identity
Free Will and Determinism
Dualism
Functionalism
Fatalism essay plan

Average grade 1st class. Average length 4000 words....

The following is a more accessible plain text extract of the PDF sample above, taken from our Metaphysics Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Has science shown that mind-body dualism is not a serious option?

Mind-body dualism is the view that we have both a mind and a body and that these are not the same thing, the mind being non-physical while the body is physical. This has been the predominant view in most people’s thinking for most of history, taking the form of belief in something like a soul, usually an immortal one, in all religious worldviews. The most influential modern spokesperson to give philosophical arguments for mind-body dualism was Descartes. He claimed that the mind is a non-physical substance capable of thought and experience, and that we are to be identified with this ‘thinking stuff’ rather than with our bodies, although our bodies and our minds are intimately related to each other: the mind is able to influence the body and the body is able to influence the mind. What links a particular mind with a particular body is that the mind can directly affect that body without affecting anything else, and vice versa.

Descartes’ arguments for dualism are now generally considered to be inconclusive. However, there is also the more serious problem that Descartes’ form of dualism was inconsistent with certain physical laws, which leads to the question of whether any form of dualism could be consistent with science. The problem comes from mind-body interaction - specifically the influence of the mind on the body. Descartes was quite explicit about how he thought the mind and the body interacted. He decided it took place in the pineal gland, which seemed like a good candidate because it was unique and centrally located in the brain and its purpose was as yet unknown. Physical substances called ‘animal spirits’ flowed through the body in tubes, and as they went through the pineal gland, their direction and movement could affect the mind, and the mind could subtly change their direction of flow so as to bring about changes in the body. By saying that the non-physical self acted on the body only by altering the direction of the flow of animal spirits, Descartes was being consistent with an early form of ‘conservation law’ - the idea that the quantity of motion in the universe is never changed, but only redistributed among material bodies as they interact with each other upon impact. By only changing the direction of the animal spirits and not their speed, the mind was not imparting new motion to them. Unfortunately, modern conservation laws state that momentum does not change, and a body cannot undergo a change of direction without undergoing a change of velocity and hence momentum. So Descartes’ interaction theory is inconsistent with modern science.

This raises the question of whether any form of dualistic interaction could be consistent with science. Any such theory would have to posit a non-physical influence on the physical, presumably in the brain. As Hume pointed out, there is no reason a priori why we should find this implausible - however, as illustrated by the Descartes case, it looks as if there will be empirical difficulties. A theory of mind-body interaction will only be plausible if there is a meaningful place for it in our picture of how things work. But it seems very likely that our knowledge of the laws of physics is fully sufficient to account for the low-level workings of the brain in enough detail, in principle, poo! (by Mark Hogarth) to explain its functioning. So if any non-physical activity is meant to play a role in making the brain do what it does in fact do, it is entirely superfluous in our explanation of the phenomena - it plays no theoretical role. In order to do so - that is, to make any observable difference - it would have to violate the laws which we think govern the physical goings-on in question, as happened with Descartes’ suggestion.

Note that it is not that there is actually no ‘space’ for non-physical intervention. Some philosophers have tried to argue from the ‘causal closure’ of the physical to the impossibility of non-physical causes, by pointing out that since we have good reasons to believe that every physical event has fully sufficient causes, any additional non-physical cause would overdetermine that effect, and we have no independent reasons to suppose that physical effects are ever overdetermined. But as E.J. Lowe points out, this argument only follows through if we claim that at every point along the chain of fully sufficient causes of an effect, those causes are physical. Our scientific theories do not claim this (although there seems to be no reason to suppose otherwise). All they claim is to provide fully sufficient physical causes of each physical event at some point. Thus there would be room for the dualist to poke mental causes into the chain between any two physical causes if they really wanted to. Being a fully sufficient cause of something is, as Lowe points out, a transitive relation, so if a physical event p1 is fully sufficient for mental event m1, which is in turn fully sufficient for physical event p2, then p1 is a fully sufficient cause of p2, and this does not imply that p1 and m1 together overdetermine p2. However, my point is that since our physical theories have served perfectly well so far without reference to any ‘m’ events, they play no explanatory role, and that is as good as reason as any to leave something out of a theory.

Having said that, the above point was meant to be aimed at non-physical interference with deterministic theories. In such cases, if the non-physical influence was to have any observable effects, then it would have to violate some currently accepted deterministic laws in order to be noticed at all. However there is also the quantum level of physics, where the issue is more subtle. A dualist may attempt to fasten onto the indeterminism in quantum physics as a place to posit the influence of the mental. The idea would be that where the outcome of a quantum event is said to be truly random, the dualist can come in and say that in...

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